A primary tumour of the oesophagus with both melanocytic and schwannian differentiation. Melanocytic schwannoma or malignant melanoma?

A 76 year old white woman presented with a four month history of dysphagia and weight loss. Clinical, radiological, and endoscopic examination revealed a pigmented mass in the lower third of the oesophagus. The preoperative diagnosis, including biopsy examination, was that of malignant melanoma. Following oesophageal resection, the mass was found to be a localised, relatively superficial tumour with light, electron microscopic, and immunohistochemical features common to both Schwann cells and melanocytes. The patient survived 46 months after surgery and died of a stroke, with no evidence of tumour recurrence. The tumour is presented as a case of melanocytic schwannoma, with unique features when compared with oesophageal melanotic schwannomas and malignant melanomas described in the literature. The differential diagnosis is discussed and an origin from a common precursor cell of neural crest origin is postulated.     

Nucleolar organizer regions in transitional cell tumors of the bladder

The traditional silver staining technique that identifies nucleolar organizer region-associated proteins has recently been adapted and applied to paraffin sections, and used to examine changes in nucleolar organizer region numbers in a variety of benign and malignant conditions. We describe herein the enumeration of nucleolar organizer regions in a variety of benign and malignant conditions of the transitional epithelium of the urinary bladder. While there is a statistical separation between normal and neoplastic groups, there is a degree of overlap between normal, inflammatory, dysplastic, and neoplastic urothelium.     

Distribution of mutations in the PEX gene in families with X-linked hypophosphataemic rickets (HYP)

Mutations in the PEX gene at Xp22.1 (phosphate-regulating gene with homologies to endopeptidases, on the X-chromosome), are responsible for X-linked hypophosphataemic rickets (HYP). Homology of PEX to the M13 family of Zn2+ metallopeptidases which include neprilysin (NEP) as prototype, has raised important questions regarding PEX function at the molecular level. The aim of this study was to analyse 99 HYP families for PEX gene mutations, and to correlate predicted changes in the protein structure with Zn2+ metallopeptidase gene function. Primers flanking 22 characterised exons were used to amplify DNA by PCR, and SSCP was then used to screen for mutations. Deletions, insertions, nonsense mutations, stop codons and splice mutations occurred in 83% of families screened for in all 22 exons, and 51% of a separate set of families screened in 17 PEX gene exons. Missense mutations in four regions of the gene were informative regarding function, with one mutation in the Zn2+-binding site predicted to alter substrate enzyme interaction and catalysis. Computer analysis of the remaining mutations predicted changes in secondary structure, N-glycosylation, protein phosphorylation and catalytic site molecular structure. The wide range of mutations that align with regions required for protease activity in NEP suggests that PEX also functions as a protease, and may act by processing factor(s) involved in bone mineral metabolism.      

Hypescheme: an operational criteria checklist and minimum data set for molecular genetic studies of attention deficit and hyperactivity disorders

Investigators engaged in mapping the genetic basis of attention deficit hyperactivity disorder (ADHD) currently use a number of measures for the collection of clinical information. This gives rise to difficulties in comparing datasets and research communications between independent groups. This paper describes the development of Hypescheme, which is an operational criteria checklist for ADHD, oppositional defiant disorder (ODD), and conduct disorder (CD), and is proposed as a minimum dataset for those engaged in molecular genetic studies of ADHD. Hypescheme consists of a computerised data checklist system that includes all the operational criteria required for both DSM-IV and ICD-10 diagnostic criteria and a systematic record of information about comorbid psychiatric, developmental, and neurological disorders. Using this data, an algorithm applies both DSM-IV and ICD-10 criteria to generate operational diagnostics under both these systems. Hypescheme is not designed to replace current assessment protocols but to be a final common checklist that can be completed by experienced researchers using all available data.     

Molecular mechanism of kNBC1–carbonic anhydrase II interaction in proximal tubule cells

We have recently shown that carbonic anhydrase II (CAII) binds in vitro to the C-terminus of the electrogenic sodium bicarbonate cotransporter kNBC1 (kNBC1-ct). In the present study we determined the molecular mechanisms for the interaction between the two proteins and whether kNBC1 and CAII form a transport metabolon in vivo wherein bicarbonate is transferred from CAII directly to the cotransporter. Various residues in the C-terminus of kNBC1 were mutated and the effect of these mutations on both the magnitude of CAII binding and the function of kNBC1 expressed in mPCT cells was determined. Two clusters of acidic amino acids, L⁹⁵⁸DDV and D⁹⁸⁶NDD in the wild-type kNBC1-ct involved in CAII binding were identified. In both acidic clusters, the first aspartate residue played a more important role in CAII binding than others. A significant correlation between the magnitude of CAII binding and kNBC1-mediated flux was shown. The results indicated that CAII activity enhances flux through the cotransporter when the enzyme is bound to kNBC1. These data are the first direct evidence that a complex of an electrogenic sodium bicarbonate cotransporter with CAII functions as a transport metabolon.     

The mutational spectrum of brachydactyly type C

Growth/differentiation factor-5 (GDF5), also known as cartilage-derived morphogenetic protein-1 (CDMP-1), is a secreted signaling molecule that participates in skeletal morphogenesis. Heterozygous mutations in GDF5, which maps to human chromosome 20, occur in individuals with autosomal dominant brachydactyly type C (BDC). Here we show that BDC is locus homogeneous by reporting a GDF5 frameshift mutation segregating with the phenotype in a family whose trait was initially thought to map to human chromosome 12. We also describe heterozygous mutations in nine additional probands/families with BDC and show nonpenetrance in a mutation carrier. Finally, we show that mutant GDF5 polypeptides containing missense mutations in their active domains do not efficiently form disulfide-linked dimers when expressed in vitro. These data support the hypothesis that BDC results from functional haploinsufficiency for GDF5.     

Preferrential rearrangement in normal rabbits of the 3' VHa allotype gene that is deleted in Alicia mutants; somatic hypermutation/conversion may play a major role in generating the heterogeneity of rabbit heavy chain variable region sequences

The rabbit is unique in having well-defined allotypes in the variable region of the heavy chain. Products of the VHa locus, (with alleles a1, a2, and a3), account for the majority of the serum immunoglobulins. A small percentage of the serum immunoglobulins are a-negative. In 1986, Kelus and Weiss described a mutation that depressed the expression of the Ig VH a2 genes in an a1/a2 rabbit. From this animal the Alicia rabbit strain was developed and the mutation was termed ali. We previously showed, using Southern analysis and the transverse alternating field electrophoresis technique, that the difference between the ali rabbit and normal is a relatively small deletion including some of the most 3' VH genes. The most JH proximal 3' VH1 genes in DNA from normal rabbits of a1, a2 and a3 haplotypes encode a1, a2 and a3 molecules respectively, and it has been suggested that these genes are responsible for allelic inheritance of VHa allotypes. The present study suggests that the 3' end of the VH locus probably plays a key role in regulation of VH gene expression in rabbits because VH gene(s) in this region are the target(s) of preferential VDJ rearrangements. This raises the possibility that mechanisms such as somatic gene conversion and hypermutation are at work to generate the antibody repertoire in this species. Our data support the view that the 3' VH1 gene may be the preferred target for rearrangement in normal rabbits, and for the normal chromosome in heterozygous ali animals. However, homozygous ali rabbits with a deletion that removed the a2-encoding VH1 on both chromosomes do survive, rearrange other VH genes and produce normal levels of immunoglobulins as well as a significant percentage of B cells which bear the a2 allotype. This challenges the view that one VH gene, VH1, is solely responsible for the inheritance pattern of VHa allotypes.     

The relationship of childhood sexual abuse and depression with somatic symptoms and medical utilization

BACKGROUND: Previous research suggests that childhood sexual abuse is associated with high rates of retrospectively reported medical utilization and medical problems as an adult. The goal of this study was to determine if abused females have higher rates of medical utilization using self-report and objective measures, compared with non-abused females. A further goal was to determine whether findings of prior research would be replicated when childhood physical abuse level was controlled. This study also examined the moderating impact of depressed mood on current health measures in this population. METHODS: Six hundred and eight women recruited from a health maintenance organization completed self-report measures of health symptoms for the previous month and doctor visits for the previous year. Objective doctor records over a 2 year period were examined for a subset of 136 of these women. RESULTS: Results showed significantly more self-reported health symptoms and more self-reported doctor visits in abused participants compared with those who reported no childhood history of sexual abuse. Objective doctor visits demonstrated the same pattern with abused participants exhibiting more visits related to out-patient surgery and out-patient internal medicine. In addition, persons who were both sexually abused and depressed tended to visit the emergency room more frequently and to have more in-patient internal medicine and ophthalmology visits than sexually abused participants who reported low depressed mood and non-abused controls. CONCLUSIONS: These results replicate prior studies and suggest that current depression may moderate the relationship between sexual abuse and medical problems in adulthood.     

Phorbol ester-induced inhibition of the beta-adrenergic system in pulmonary endothelium: role of a pertussis toxin-sensitive protein

To investigate possible cellular mechanisms for how activation of protein kinase C inhibits the relaxation caused by isoproterenol, we studied the effect of the protein kinase C activator 4 beta-phorbol-12 beta-myristate-13 alpha-acetate (PMA) on the increase in cyclic AMP (cAMP) production and adenylate cyclase activity caused by isoproterenol in bovine pulmonary artery endothelial cells. Treatment of intact cells with PMA prevented in a time- and dose-dependent manner the increase in cAMP production caused by isoproterenol, whereas 4 alpha-phorbol-12 beta-myristate-13 alpha-acetate (4 alpha-PMA), which does not activate protein kinase C, did not affect isoproterenol-induced cAMP production. PMA also reduced the increase in adenylate cyclase activity caused by isoproterenol, forskolin, and Gpp(NH)p. To test the hypothesis that the inhibitory effect of PMA is mediated via a pertussis toxin-sensitive G protein, we determined whether pretreatment of the cells with pertussis toxin would prevent the inhibitory effects of PMA. In pulmonary endothelial cells, pertussis toxin ADP-ribosylated an Mr 40,000 peptide that comigrated with the pertussis toxin substrate of human erythrocytes. Pertussis toxin treatment eliminated the inhibitory effect of PMA on isoproterenol-stimulated cAMP production and adenylate cyclase activity. Thus, the protein kinase C activator PMA inhibits the increase in cAMP production and adenylate cyclase caused by isoproterenol. This inhibitory effect in endothelial cells appears to be mediated via a pertussis toxin-sensitive protein.